Title : Effect of preparation of raw material mixture on purity of tricalcium aluminate through solid state synthesis
Abstract:
In the cement industry, refined fuels are increasingly being replaced by alternative fuels. This replacement not only brings economic and ecological benefits but also a lot of technological problems, which consist in increasing the content of some chemical elements that cause variability in the mineralogical composition. This is subsequently reflected in the properties of Portland clinker. The synthesis of pure clinker minerals is therefore crucial both for the study of their behaviors in industrially produced cement and for the preparation of analytical standards for the identification of minerals through XRD. The research goal is focused on preparing the pure clinker mineral tricalcium aluminate in laboratory conditions using a simple laboratory methodology using solid-state synthesis. It closely monitors the effect of the raw material mixture homogenization process on the purity of the prepared mineral. A high-speed Pulverisette 6 planetary mill and 2 types of grinding bodies were used to homogenize the tricalcium aluminate raw material mixture. A corundum grinding capsule with corundum grinding bodies to prevent contamination by foreign ions and a very efficient steel grinding capsule with steel grinding bodies were used. The raw material mixture was fired at 6 different temperatures from 1200 to 1450 °C, and the prepared mineral's purity was quantified using Rietveld analysis. The results of laser granulometry show that in both cases of grinding, there was a very similar comminution of the raw material. Iron contamination based on XRF analysis was shown to be minimal at only 0.21%. The highest purity of 97.6% C3A was achieved at a temperature of 1450 °C when grinding in a steel grinding capsule, 2.4% represents unreacted lime. When grinding in a corundum capsule, a purity of the mineral of 93.6% was achieved with a residue of the mineral mayenite of 2.2% and lime of 3.8 The reason may be the insufficient degree of comminution of the raw material in the corundum capsule. On the other hand, a slight iron contamination during the grinding of raw material mixture had a positive effect on the purity, where the iron acted as a flux and caused a better reaction of the mineral mayenite.
Audience Take Away Notes:
- The audience will be introduced to a very simple methodology for the preparation of clinker mineral through solid state synthesis
- Demonstration of the importance of the preparation process within the homogenization of raw material mixture for solid state reactions
- This method is easily reproducible and can be used in the preparation of other clinker minerals in laboratory conditions
